While girls' use of cigarettes, alcohol and marijuana is less than that of boys in the early elementary years, the prevalence of girls' substance use quickly catches up to and surpasses that of boys by 8th grade. The proposed study is a pilot for a primary study investigating the processes related to the initiation and escalation of substance use among girls in early adolescence focusing on three domains, stressful events, pubertal maturation and timing, and hormonal influences. In the general model guiding the primary study, these domains are related to early substance use among girls through daily affect, aggression, depression, and affiliation with substance using peers. The specific aims of this study are: (1) to examine the feasibility of an intensive multi-method assessment conducted with 5th and 8th grade girls and their mothers assessing girls' life stress, emotional responses, pubertal maturation and hormones across the menstrual cycle. (2) To examine the variability, reliability and validity of daily and weekly measures of emotional responses, as measured by daily affect ratings, association with substance-using peers, and affiliative coping, for 5th and 8th grade girls and to examine the amount and timing of daily and weekly data required to obtain adequate samples of these variables and hormonal levels. We will also assess the psychometric properties of some of our questionnaire-based measures, with a particular focus on the 5th grade sample. (3) To obtain estimates of effect sizes for: (a) between participant bivariate relations among chronic and episodic stressful events, hormonal levels, and precursors to substance use as a function of grade (5 vs. 8th) and pubertal timing (early vs. on-time/late); and between these variables and early substance use for 8th graders; and (b) within participant bivariate relations between hormonal levels, emotional responses, affiliative coping, and affiliation with substance-using peers, as a function of grade and pubertal timing. To address these aims, we will assess 80 girls, 40 in both the 5th and 8th grade, with 20 early maturers in each grade using multiple methods, including questionnaires completed by both mothers and girls, a Life Stress Interview to assess chronic and episodic stress, and an assessment of the girls' physical maturation by a female nurse. For a minimum of four weeks, we will obtain weekly measures of estradiol, testosterone, progesterone and cortisol, as well as momentary and end of day assessments using an Electronic Personal Data Assistant (PDA). All assessments will be timed to menstruating girls' menstrual cycle, with timing of non-menstruating girls yoked to that of menstruating girls. [unreadable] [unreadable]